Conventionally, communicating apparatuses (for example, cell phones and notebook personal computers) having wireless interfaces for W-CDMA (Wideband-Code Division Multiple Access), WLAN (Wireless Local Area Network), one-segment broadcasting etc. have been popular. When using the wireless interface, such a communicating apparatus suffers from problems, such as deterioration of transmission band and interruption of communication caused by radio noise entering to the antenna of a wireless module from the inside of the main body.
In recent years, there has appeared an analog chip which picks up radio noise (a noise signal) near a noise source and cancels the radio noise from a reception signal (see, for example, Japanese Laid-Open Patent Publication No. 2004-236171). Moreover, as a method for canceling the radio noise from a reception signal, for example, there is a known method in which the radio noise is cancelled by inverting the phase of the noise signal from the noise source and adding the resulting signal to a reception signal as illustrated in FIG. 1 (see, for example, Japanese Laid-Open Patent Publication No. 08-335915).
FIG. 1 is a schematic view for explaining the prior art. In the example shown in FIG. 1, I and Q signals to be inputted into a phase and amplitude adjustment IC are combined to optimize communication quality information (for example BER: Bit Error Rate) outputted from a GPS (Global Positioning System) receiver module, and the phase and amplitude adjustment IC inverts the phase of a noise signal based on the I and Q signals and adds the resulting phase-inverted noise signal to a reception signal. Consequently, the radio noise is optimally cancelled from the reception signal.